The present invention relates to a looper drive for sewing machines, such as chainstitch sewing machines.
A looper drive is known from German patent specification No. 34 43 294. This device used for adjusting the travel of the upper looper in overedging sewing machines incorporates a cylindrical bushing with a diametral hole which carries a rod on which the upper looper is mounted. The cylindrical bushing is snugly received in an opening of a support member which, in turn, has two opposite slots for the looper shaft to pass through. The device according to the afore-mentioned application provides for an upper looper travel adjusting means which allows the axis of the swivel link to move upwards or downwards.
U.S. Pat. No. 3,670,677 relates to a device in which the looper shaft is movably guided in a drum member which, in turh, is snugly received in the opening of a support. The support also has two slots through which the looper shaft extends.
Due to the slots the two aforementioned devices have a disadvantage in that lint built up by the thread and the fabric during the sewing operation accumulates in the slots of the support members.
This prevents lint-free lubrication of the looper shaft bearing means since the lubricating means will blend with the lint producing an abrasive effect which contributes to excessive wear of the looper shaft and its bearing means.